GaN-based laser diode structure

Abstract

The utility model relates to a GaN-based laser diode structure, which comprises a GaN substrate, an epitaxial layer is grown on the substrate, and the epitaxial layer comprises a lower covering layer, a lower waveguide layer, a quantum well, an upper waveguide layer, an electron blocking layer, an upper covering layer and an epitaxial contact layer which are sequentially arranged from bottom to top; an ohmic contact layer is arranged on the epitaxial layer, a metal covering layer is plated on the ohmic contact layer, a ridge structure close to a vertical angle is manufactured along the metal covering layer, the ohmic contact layer, the epitaxial contact layer and the upper covering layer, an insulating layer covers the ridge structure, an electron blocking layer covers the ridge structure, a P electrode covers the outer side of the insulating layer, and a substrate is thinned. And manufacturing an N electrode to form a laser diode structure. According to the utility model, ITO is used as an ohmic contact layer, and Pd is matched to be used as a photoetching mask plate; a right-angle surface is formed by utilizing a larger ITO lateral etching angle and combining with a Pd mask; good ohmic contact and a ridge structure close to a vertical angle can be formed, and a good optical limiting effect is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a semiconductor laser technical field especially relates to a kind of GaN-based laser diode structure. BACKGROUND

[0002] Small power edge-emitting laser diode, under small current operation, must realize lower threshold current, and form single-mode laser, the ridge width of conventional small power GaN single-mode laser diode is below 2um, and the height of ridge is close to 1um;In order to form good light field restriction effect, the angle of ridge is required to be close to right angle.

[0003] The angle of ridge is formed by using ITO as contact and using photoresist as mask plate, which is easy to cause mode leakage and large light loss;While using Pd as ohmic contact metal and forming photoetching mask plate, a better angle can be formed, but the cost is high and the light restriction is affected.The utility model provides a kind of GaN-based laser diode structure, uses ITO as ohmic contact layer, and matches Pd as photoetching mask plate;ITO side etching angle is larger, combined with Pd mask, to form a right angle surface;Good ohmic contact and ridge structure close to vertical angle can be formed, and better optical restriction effect is achieved. SUMMARY

[0004] Based on the technical problems existing in the background art, the utility model provides a kind of GaN-based laser diode structure, uses ITO as ohmic contact layer, and matches Pd as photoetching mask plate;ITO side etching angle is larger, combined with Pd mask, to form a right angle surface;Good ohmic contact and ridge structure close to vertical angle can be formed, and better optical restriction effect is achieved.

[0005] The utility model provides a kind of GaN-based laser diode structure, including GaN substrate, substrate growth epitaxial layer, epitaxial layer includes from below to above sequentially arranged lower cover layer, lower waveguide layer, quantum well, upper waveguide layer, electron blocking layer, upper cover layer and epitaxial contact layer;Epitaxial layer is equipped with ohmic contact layer, the ohmic contact layer is plated film metal cover layer, along metal cover layer, ohmic contact layer, epitaxial contact layer, upper cover layer is made close to vertical angle ridge structure, in ridge structure covers insulating layer, and covers electron blocking layer, P electrode is covered outside insulating layer, substrate is thinned, and N electrode is made to form laser diode structure.

[0006] Preferably, the lower cover layer is made of N-type AlGaN, the lower waveguide layer is made of N-type InGaN, the quantum well is made of InGaN, the upper waveguide layer is made of P-type InGaN, the electron blocking layer is made of P-type AlGaN, the upper cover layer is made of P-type AlGaN, the epitaxial contact layer is made of P-type GaN, and the insulating layer is made of SiO2 insulating layer.

[0007] Preferably, ITO layer is plated on the epitaxial layer, annealing forms an ohmic contact layer; the metal covering layer is mainly Pd.

[0008] Preferably, ITO is used as the ohmic contact layer, and Pd is used as the photolithography mask plate; the boundary of ITO is smaller than that of Pd, and the ITO has a larger etching angle, and the ridge structure with a right angle surface is formed by combining the Pd mask.

[0009] Preferably, the refractive index of ITO is 1.8, which is lower than that of GaN.

[0010] The beneficial effects of the utility model are as follows: ITO is used as the ohmic contact layer, and Pd is used as the photolithography mask plate; the refractive index of ITO is relatively low, and the refractive index is 1.8, which is much lower than the refractive index 2.4 of GaN, and the absorption rate is very low in the blue-green light wave band, the thickness of the epitaxial layer can be reduced, and better optical limiting effect is realized; the ITO has a larger etching angle, and the ridge structure with a right angle surface is formed by combining the Pd mask; better ohmic contact and the ridge structure with a nearly vertical angle can be further formed, and better optical limiting effect is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 An initial structure schematic diagram of a GaN-based laser diode structure is provided for the utility model;

[0012] Figure 2 A processed structure schematic diagram of a GaN-based laser diode structure is provided for the utility model;

[0013] Figure 3 An ITO and Pd composite structure schematic diagram is provided for the utility model.

[0014] In the figure, 1 is a substrate, 2 is a lower covering layer, 3 is a lower waveguide layer, 4 is a quantum well, 5 is an upper waveguide layer, 6 is an electron blocking layer, 7 is an upper covering layer, 8 is an epitaxial contact layer, 9 is an ohmic contact layer, 10 is a metal covering layer, 11 is a ridge structure, 12 is an insulating layer, 13 is a P electrode, and 14 is an N electrode. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model, and obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments.

[0016] REFERENCE Figures 1-2A GaN-based laser diode structure, comprising a GaN substrate 1, an epitaxial layer grown on the substrate 1, the epitaxial layer comprising, from bottom to top, a lower cladding layer 2, a lower waveguide layer 3, a quantum well 4, an upper waveguide layer 5, an electron blocking layer 6, an upper cladding layer 7 and an epitaxial contact layer 8; an ohmic contact layer 9 is arranged on the epitaxial layer, a metal cladding layer 10 is plated on the ohmic contact layer 9, a ridge structure 11 with a near-vertical angle is formed along the metal cladding layer 10, the ohmic contact layer 9, the epitaxial contact layer 8 and the upper cladding layer 7, an insulating layer 12 is arranged on the ridge structure 11 and covers the electron blocking layer 6, a P electrode 13 is arranged outside the insulating layer 12, the substrate 1 is thinned, and an N electrode 14 is formed to form the laser diode structure. The lower cladding layer 2 is made of N-type AlGaN, the lower waveguide layer 3 is made of N-type InGaN, the quantum well 4 is made of InGaN, the upper waveguide layer 5 is made of P-type InGaN, the electron blocking layer 6 is made of P-type AlGaN, the upper cladding layer 7 is made of P-type AlGaN, the epitaxial contact layer 8 is made of P-type GaN, and the insulating layer 12 is made of a SiO2 insulating layer.

[0017] The utility model discloses adopt the epitaxial layer on plating ITO layer, anneal and form ohmic contact layer 9, metal cladding layer 10 is mainly metal structure with Pd. Specifically, adopt ITO as ohmic contact layer 9, and match Pd as photolithography mask plate, the boundary of ITO is less than the boundary of Pd, utilize ITO side etching angle is bigger, combine Pd mask, form the ridge structure 11 of right angle face.

[0018] The utility model discloses still proposed a kind of preparation method of GaN-based laser diode structure, comprising the following steps:

[0019] S1, epitaxial growth: with gallium nitride substrate, epitaxial layer is grown on substrate 1, and the epitaxial layer includes lower cladding layer n-type AlGaN, lower waveguide layer n-type InGaN, quantum well InGaN, upper waveguide layer p-type InGaN, electron blocking layer p-type AlGaN, upper cladding layer p-type AlGaN and epitaxial contact layer P-type GaN;

[0020] S2, epitaxial layer plating ITO layer, anneal and form ohmic contact layer, and plating metal cladding layer, mainly metal structure with Pd;

[0021] S3, ridge structure is made, ridge structure 11 with near-vertical angle is made along metal cladding layer 10, ohmic contact layer 9, epitaxial contact layer 8, upper cladding layer 7, specifically, adopt ITO as ohmic contact layer 9, and match Pd as photolithography mask plate, the boundary of ITO is less than the boundary of Pd, utilize ITO side etching angle is bigger, combine Pd mask, form the ridge structure 11 of right angle face;

[0022] S4, cover SiO2 insulating layer;

[0023] S5, making P electrode; thinning GaN substrate, making N electrode;

[0024] S6, finally, making crack, making resonant cavity on the side of chip, forming laser diode.

[0025] The above merely provides the preferred embodiment of the present application, and the protection scope of the present application is not limited to this. Any skilled person in the art, according to the technical scheme and the inventive concept of the present application, can make equivalent substitution or change within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A GaN-based laser diode structure comprising a substrate (1), characterized in that, The substrate (1) is grown with an epitaxial layer, which includes, from bottom to top, a lower cladding layer (2), a lower waveguide layer (3), a quantum well (4), an upper waveguide layer (5), an electron blocking layer (6), an upper cladding layer (7) and an epitaxial contact layer (8); an ohmic contact layer (9) is provided on the epitaxial layer, a metal cladding layer (10) is plated on the ohmic contact layer (9), a ridge structure (11) with a near-vertical angle is formed along the metal cladding layer (10), the ohmic contact layer (9), the epitaxial contact layer (8) and the upper cladding layer (7), an insulating layer (12) is provided on the ridge structure (11) and covers the electron blocking layer (6), a P electrode (13) is provided outside the insulating layer (12), the substrate (1) is thinned, an N electrode (14) is formed to form a laser diode structure.

2. The GaN-based laser diode structure of claim 1, wherein, The lower cladding layer (2) is made of N-type AlGaN, the lower waveguide layer (3) is made of N-type InGaN, the quantum well (4) is made of InGaN, the upper waveguide layer (5) is made of P-type InGaN, the electron blocking layer (6) is made of P-type AlGaN, the upper cladding layer (7) is made of P-type AlGaN, the epitaxial contact layer (8) is made of P-type GaN, and the insulating layer (12) is made of SiO2 insulating layer.

3. The GaN-based laser diode structure of claim 1, wherein, An ITO layer is plated on the epitaxial layer, and annealing is performed to form the ohmic contact layer (9); the metal cladding layer (10) is a metal structure mainly composed of Pd.

4. The GaN-based laser diode structure of claim 3, wherein, ITO is used as the ohmic contact layer (9) and is matched with Pd as a photolithography mask plate; the boundary of ITO is smaller than that of Pd, and the etching angle of ITO is larger, which, combined with the Pd mask, forms a ridge structure (11) with a right angle surface.

5. The GaN-based laser diode structure of claim 4, wherein, The refractive index of ITO is 1.8, which is lower than that of GaN.

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